Alleging intelligence failure behind the serial blasts in the capital, the Bharatiya Janata Party on Saturday demanded that the government take all "actions and precautions" to prevent their recurrence.

"Delhi has become the den of terrorists. Hundreds of terrorists, ISI agents and Pakistanis have been arrested and huge quantity of arms and explosives including RDX seized in the recent past. Necessary precautions should have been taken by the authorities," BJP's Deputy Leader in Lok Sabha V K Malhotra told PTI.

"We have repeatedly raised in Parliament that Delhi was sitting on a volcano. The Home Ministry and Intelligence agencies have totally failed," he said.